Developments have been seen in the field of projectile launching apparatuses, such as air rifles, pneumatic guns, pellet rifles, paintball guns and the like. Paintball guns have been around for many years and have seen numerous evolutionary changes over the years. The most common mechanisms for launching projectiles, such as pellets, BB bullets and paintballs use energy of a compressed gas or a spring. However, there are variety of mechanisms described in the prior art for launching these projectiles. Such mechanisms include use of a stored compressed gas in a form of carbon dioxide cylinders or other high pressure storage tanks, use of a powerful spring to push a piston which compresses air to push a projectile, use of a hand pump to pressurize the air for subsequent release, and use of a direct acting means such as a solenoid plunger or a centrifugal force to push the projectile out of a barrel. The above mentioned mechanisms generally suffer from a number of disadvantages as explained below.
The mechanism of using stored compressed gas, such as carbon dioxide requires a storage means, such as a tank, a gas chamber, or a canister. The use of the storage means involves a cumbersome method of filling a gas in the storage means and transporting of the storage means based projectile launching apparatus. Additionally, the use of such storage means require additional equipments such as regulators, evaporation chambers, and other controls to reduce the pressure of the stored compressed gas for a safe launching of the projectiles. The requirement of such additional equipments increases the cost and the complexity of a projectile launching apparatus. In a typical projectile launching apparatus, which uses the storage means, velocity of the projectile varies significantly depending on the temperature of the storage means. For example, a pressure of the carbon dioxide gas depends upon the temperature of the canister, containing the carbon dioxide gas. Furthermore, the storage means stored with a large amount of compressed gas may cause potential safety hazard by a sudden release of compressed gas due to a fault in the storage means.
U.S. Pat. Nos. 6,516,791, 6,474,326, 5,727,538 and 6,532,949 describe various ways of porting and controlling of high pressure gas supply to improve the reliability of projectile launching apparatuses, specifically, guns. The controlling of the high pressure gas supply is achieved by differentiating air streams, such as an air stream which is delivered to a bolt to facilitate the chambering of the projectile in a barrel and an air stream which pushes the projectile out of the barrel. However, all the above listed US patents suffer from major inconvenience and potential safety hazard of storing a large volume of a highly compressed gas within the guns. Additionally, these guns combine an electronic control coupled with the propulsion method driving mechanism of stored compressed gas, which tend to increase the inherent complexity of the mechanism used in the gun, as well as, increase the cost and reliability issues.
The another mechanism which has been used for quite a few years in many different types of pellet, “BB bullets” or air guns has a basic principle of storing energy in a spring, which is subsequently released to rapidly compress gas, especially air present in the atmosphere. The highly compressed gas is generated by the spring acting on a piston to push the projectile out of the barrel at a high velocity. Problems with such mechanism include the need to “cock” the spring between successive shots and thereby limiting such guns to be a single shot device or a gun with a low rate of firing. Further, unwinding of the spring results in a double recoil effect. The first recoil is from the initial forward movement of the spring and the second recoil when the spring slams the piston into an end of a cylinder (i.e. forward recoil).
A typical gun including the spring requires a significant amount of maintenance and, if dry-fired (without projectile), the mechanism is easily damaged. Finally, the effort required for such “cocking” is often substantial and can be difficult for many individuals. References to these guns are found in U.S. Pat. Nos. 3,128,753, 3,212,490, 3,523,538, and 1,830,763. Additional variation on the above mechanism has been attempted through the years including using an electric motor to cock the spring that drives the piston. This variation is introduced in U.S. Pat. Nos. 4,899,717 and 5,129,383. While this variation solves the problem of cocking effort, the resulting air gun still suffers from a complicated mechanism, the double recoil effect and the maintenance issues associated with such a spring piston system. A further mechanism which uses a motor to wind the spring is described in U.S. Pat. Nos. 5,261,384 and 6,564,788, issued to Hu.
Hu's patents disclose a motor for compressing a spring, where the motor is connected to a piston. The spring is quickly released such that the spring drives the piston to compress the air, which pushes the projectile out the barrel. This implementation still suffers from similar limitations inherent in the spring piston systems. Hu describes the use of the motor to wind the spring in the above listed patents. Specifically, the spring must quickly compress the air against the projectile to force the projectile out of the barrel at a high velocity. This requires a strong spring to rapidly compress the air when the piston releases. Springs in such systems are highly stressed mechanical element which are prone to breakage and also increase the weight of the air gun. A further disadvantage of Hu's patents is that the spring is released from a rack pinion under full load causing tips of gear teeth to undergo severe tip loading. This causes high stress and wear on the mechanism especially on the gear teeth. This is a major complaint for those guns in the commercial market and is a major reliability issue with this mechanism.
A further disadvantage of this type of mechanism is that for launching a larger projectile or a projectile requiring a high velocity of launch, there occurs much increased wear and forward recoil, which is the result of the piston impacting the front end of the cylinder. In the dry fire, the mechanism can be damaged as the piston slams against the face of the cylinder. Hu describes use of a breech shutoff that is common in virtually all toy guns since the air must be directed down the barrel and the flow into a projectile inlet port must be minimized. Further, Hu specifically does not incorporate an air compression valve in the above listed patents, which is a restrictive valve against which the piston compresses the air for subsequent releases. Thus, forward recoil, high wear and low power are drawbacks in this type of mechanism. A similar reference can be seen in U.S. Pat. No. 1,447,458, which shows a spring winding and then delivery to a piston to compress air and propel a projectile. In this case, the device is for non-portable operation.
The additional mechanism, which uses hand pumps to pressurize the air, is often used in low end devices. The use of such mechanism suffers from a need to pump the air between 2 to 10 times to build up enough air supply for a sufficient projectile launch velocity. This again limits the gun, such as the paintball gun to slow rates of fire. Additionally, because of the delay between as to when the air is compressed and when the compressed air is released to the projectile causes variations in the projectile launch velocity.
Further, U.S. Pat. Nos. 2,568,432 and 2,834,332 describe a mechanism to use a solenoid to directly move the piston, which compresses the air and launches the projectile out of the barrel. While this mechanism solves the obvious problem of manually pumping a chamber up in order to fire a gun, but devices incorporating this mechanism suffer from the inability to store sufficient energy in the compressed air. The solenoid may be an inefficient device and capable of converting a very limited amount of energy in the compressed air due to their operation. Furthermore, since the compressed air is applied directly to the projectile in this mechanism similar to the spring piston mechanism, the projectile begins to move as the air starts being compressed. This limits the ability of the solenoid to store energy in the compressed air to a very short time period and therefore these devices cater to low energy guns.
In order to improve the design, the piston must actuate in an extremely fast time frame in order to prevent significant projectile movement during a compression stroke. This results in a very suitable piston mass similar to the spring piston designs which results in the undesirable double recoil effect as the piston mass must come to a halt. Additionally, when this mechanism suffers from dry-fire the air is communicated to the atmosphere through the barrel causing damage to the mechanism. Another variant of this approach is disclosed in U.S. Pat. No. 1,375,653, which uses an internal combustion engine instead of the solenoid to act against the piston. Although this solves the issue of sufficient power, but the use of the internal combustion engine is no longer considered as an air rifle as it becomes a combustion driven gun. Moreover, the use the internal combustion engine suffers from the aforementioned disadvantages including complexity and difficulty in controlling the firing sequence.
U.S. Pat. Nos. 4,137,893 and 2,398,813 issued to Swisher discloses an air gun using an air compressor coupled to a storage tank, which is then coupled to the air gun. Although this solves the issue of double recoil effect, but is not suitable to a portable system due to inefficiencies of compressing the air and a large tank volume required. This type of air gun is quite similar to an existing paintball gun in which the air is supplied via the air tank and not compressed on demand. Using air in this fashion is inefficient and is not suitable for a portable operation since much of compressed air energy is lost to the environment through the air tank via cooling. Forty percent or more (depending on the compression ratio) of the compressed air energy is stored as heat and is lost to do work when the air is allowed to cool. Furthermore, additional complexity and expenses are required to regulate the air pressure from the air tank so that the projectile launch velocity is controlled. A variation of the above described mechanism is use of a direct air compressor as described in U.S. Pat. No. 1,743,576. Again, due to the large volume of air between compression means and the projectile, much of the compressed air energy especially, a heat of compression, is lost leading to inefficient operation. Additionally, the U.S. Pat. No. 1,743,576 teaches a continuously operating device which suffers from a significant lock time (time between a trigger pull in order to initiate the launch and the projectile leaving the barrel) as well as the inability to run in a semiautomatic or single shot mode. Further, disadvantages of this mechanism include the pulsating characteristics of the compressed air, which are caused by the release and reseating of a check valve during normal operation.
U.S. Pat. Nos. 1,343,127 and 2,550,887 disclose a mechanism to use a direct mechanical action on the projectile. Limitations of this approach include difficulty in achieving high projectile velocity since the transfer of energy must be done extreme rapidly between an impacting hammer and the projectile. Further limitations of this mechanism include a need of absorbing a significant impact as a solenoid plunger must stop and return for the next projectile. This causes the double-recoil or the forward recoil. Since the solenoid plunger represents a significant fraction of the moving mass (i.e. solenoid plunger often exceeds the projectile weight), this type of apparatus is very inefficient and limited to low velocity, such as required in low energy air guns for the purpose of toys and the like. Variations of this method include those disclosed in U.S. Pat. No. 4,694,815 in which the impact hammer is driven by a spring that contacts the projectile. The spring is “cocked” via an electric motor, but again, this does not overcome the prior mentioned limitations.
All of the currently available projectile launching apparatuses suffer from one or more of the following disadvantages. These disadvantages include, but are limited to, a manual operation by cocking a spring or pumping up an air chamber, difficulty to selectively perform single fire, semiautomatic mechanism, burst or automatic modes in these projectile launching apparatuses. Further, inconvenience, safety and consistency issues associated with refilling, transport and the use of high-pressure gas or carbon dioxide cylinders being the safety hazard. Furthermore, disadvantages include non-portability and low efficiency of these projectile launching apparatuses, which are associated with compressed air supplied from a typical air compressor. The forward recoil effects, high wear, and dry fire damage associated with a spring piston such as an electrically actuated spring piston designs. Complicated mechanisms associated with electrically winding and releasing of the spring piston design result in expensive mechanism having reliability issues. Inefficient use and/or coupling of the compressed air to the projectile also restrict their capability to launch the projectile with high velocity.
Accordingly, there exists a need for a projectile launching apparatus which includes all the advantages of the prior art and overcomes the drawbacks inherent therein.